The objective of the research in this proposal is to examine the types of visual information infants process and how that processing changes over age. More specifically, the goal of the proposed experiments is to extend the basic findings with static displays to more dynamic patterns, objects and events. In so doing, it is hoped the evidence will help to reconcile constructivist versus differentiation of infant perceptual and cognitive development. To the extent that these studies are successful, they will have made a significant contribution to the understanding of the development of infant perception and cognition. The application contains three distinct sections. In Section I we will examine developmental changes in infants' processing of a subjective contour illusion; in Section II, the development of category and collection formation, and in Section III the perception of causal events. All studies will be extensions of previous work in our laboratory and will employ some variation of an infant visual habituation procedure. The topics to be investigated represent a hierarchical arrangement of information processing skills and in each case deal with the integration of lower order parts into a more abstract whole. The subjective contour studies will examine infant perception of parts of a pattern used to form a whole pattern; the category studies, parts of an object and or types of objects used to form a single class or collection of objects; and the causality studies, the integration of individual moving objects (or in one case classes of objects) into a more abstract event.